Hello Jane and welcome to the forums!
My advice would be to try to clipping your birds wings, but do not attempt to do this if you aren’t really sure what you are doing. Clipping his wings will help you train him better because he will not be able to just fly away, therefore giving you a better shot at training him. Try to spend as much time as possible with him, and talk to him. Also, you probably should remove the mirror if he interacts with it and treats it like another bird. If he doesn’t it probably is not an issue. And try to keep hand feeding him like you mentioned as much as possible. Start by trying to hold him in his cage first as well, then progress to holding him outside of the cage. As for his diet, try finely dicing vegetables or fruits into his food box with his normal food. It will make him have to eat around the “gross stuff” and he will eventually eat some, and find out that it isn’t that bad. Note: do NOT give your bird avocado, as it is toxic to them. Good luck! Keep me updated. Hope this helped!
YellowFeather